North Korea has accused the United States of turning the Korean Peninsula into "the world's biggest hotspot" and creating "a dangerous situation in which a thermonuclear war may break out at any moment".

Key points:

The North says it is ready to react to "any mode of war desired by the US"

Mike Pence says North Korea should not test the resolve of Donald Trump

Kremlin state media says Trump is "more dangerous" than Kim Jong-un

On Monday, North Korea's deputy UN ambassador Kim In-ryong told a news conference "if the US dares opt for a military action," North Korea "is ready to react to any mode of war desired by the US".

Mr Kim said the Trump administration's deployment of the Carl Vinson nuclear carrier task group to waters off the Korean Peninsula again "proves the US reckless moves for invading the DPRK (Democratic People's Republic of Korea) have reached a serious phase of its scenario".

"The prevailing grave situation proves once again that the DPRK was entirely just when it increased in every way its military capabilities for self-defence and pre-emptive attack with a nuclear force as a pivot," he said.

Tensions have escalated over North Korean moves to accelerate its weapons development.

Mr Kim spoke as US Vice-President Mike Pence visited the tense Demilitarisation Zone dividing North and South Korea and warned Pyongyang that after years of testing the US and South Korea with its nuclear ambitions, "the era of strategic patience is over".

After 25 years of trying to deal patiently with North Korea over its nuclear program, Mr Pence said, "all options are on the table" to deal with threat, and he warned any use of nuclear weapons by Pyongyang would be met with "an overwhelming and effective response".

"Just in the past two weeks, the world witnessed the strength and resolve of our new President in actions taken in Syria and Afghanistan," Mr Pence said.

"North Korea would do well not to test his resolve or the strength of the armed forces of the United States in this region."

But Mr Kim accused the Trump administration of "trumpeting about 'peace by strength'" by deploying "one strategic striking means after another in South Korea".

He added rolling back hostile US policies toward the DPRK "is the precondition to solving all the problems in the Korean Peninsula" but said "the DPRK remains unfazed".

Trump more dangerous than Kim Jong-un: Kremlin TV

Meanwhile, as Russian hopes of strengthened ties under President Trump continue to fizzle, Kremlin state media, which hailed his election win in November, made a U-turn by arguing the new US President was "more dangerous" than Kim Jong-un.

Dmitry Kiselyov, widely seen as a top pro-Kremlin presenter who once praised Mr Trump for his "independence", said nuclear war was dangling in the hands of two "impulsive and unpredictable" personalities.

"War can break out as a result of confrontation between two personalities: Donald Trump and Kim Jong-un.

"Both are dangerous, but who is more dangerous? Trump is."

Mr Kiselyov went on to say Trump was "more impulsive and unpredictable" than the North Korean and to say both men shared some of the same negative traits: "Limited international experience, unpredictability, and a readiness to go to war."

Kremlin spokesman Dmitry Peskov declined to say whether Mr Kiselyov's views reflected the official views of the Kremlin, but said "his position is close, but not every time".

However, the fact that Mr Kiselyov is being given free rein to use such tough rhetoric about Mr Trump is nonetheless likely to reflect how deep the Kremlin's anger runs about what it sees as Mr Trump's failure to deliver on his pledge of better ties with Moscow.